docs: def _render_pages(self):
          """Render the complete document once and return the number of pages
          rendered."""
          self.style_log = StyleLog(self.stylesheet)
          self.floats = set()
          self.placed_footnotes = set()
          self._start_time = time.time()
  
          part_page_counts = {}
          part_page_count = PartPageCount()
          last_number_format = None
          for part_template in self.part_templates:
              part = part_template.document_part(self, part_page_count.count + 1)
              if part is None:
                  continue
              if part_template.page_number_format != last_number_format:
                  part_page_count = PartPageCount()
              part_page_count += part.render(part_page_count.count + 1)
              part_page_counts[part_template.name] = part_page_count
              last_number_format = part_template.page_number_format
          sys.stdout.write('\n')     # for the progress indicator
          return part_page_counts